Weft straightening mechanism for tenter frames



' F. W. HOFFMAN WEFT STRAIGHTEINING MECHANISM FOR TENTER FRAMES Feb. 8, 1955 F 2 sheets-sne l Filed Oct. 29, 1953 INVENTOR.

FREDERICK W. HOFFMAN.

ATT Y.

Feb. 8, 1955 F. w. HOFFMAN WEFT STRAIGHTENING MECHANISM FOR TENTER FRAMES Filed Oct. 29, 1,953

2 Sheets-Sheet 2 INVEN TOR.

FREDERICK W. HOFFMAN.

United States Patent WEFT STRAIGHTENING MECHANISM FOR TENTER FRAMES Frederick W. Hoffman, Pawtucket, R. I., assignor to Macknrght & Hoffman, Inc., Pawtucket, R. L, a corporation of Rhode Island Application October 29, 1953, Serial No. 389,102

1 Claim. (Cl. 2651.5)

T his invention relates to tenter frames and to other similar machines in which cloth is transversely stretched and dried prior to its delivery to winding rolls or other storage devices.

It is frequently found that the weft threads in cloth as it leaves a tenter frame are not straight or are not perpendicular to the selvage of the fabric. Scanning devices are known by which such weft displacement or skew may be detected, and roll-shifting mechanism to be controlled by such scanning devices is also known.

It is customary, however, to locate the roll shifting mechanism in the path of the cloth as it approaches the scanning devices, thus attempting to correct the displacement or skew before the cloth reaches the scanning devices. This arrangement thus fails to provide for correcting any displaced condition or skew in that portion of the cloth which is between the shifting mechanism and the scanning devices at the time when displacement is detected.

It is the general object of this invention to provide mechanism for correcting the displacement or skew after the displaced threads have passed the scanning devices. As thus constructed, no portion of the cloth can escape corrective treatment and the condition of the finished cloth is correspondingly improved. I also provide a time-lag control which permits an indicated displaced portion to reach the correcting mechanism at the precise time that the indicated correction is applied.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claim.

A preferred form of the invention is shown in the drawings, in which Fig. l is a partly diagrammatic side elevation of portions of a tenter frame having my improved straightening mechanism associated therewith;

Fig. 2 is a plan view, partly diagrammatic and showing the mechanism appearing in Fig. l; and

Fig. 3 is an end elevation of the straightening mechanism, looking in the direction of the arrow 3 in Fig. 2.

Referring to the drawings, I have shown portions of a tenter frame P which may be of any usual construction and which includes the usual tenter chains which grip the edges of the cloth C and draw these edges apart as the chains gradually diverge and approach the chain driving mechanism commonly actuated by motor M.

As the cloth gradually approaches the delivery end of the machine, the cloth is being dried at the same time that it is being stretched transversely.

As previously stated, the weft threads may be displaced from their correct position perpendicular to the selvages of the fabric, and such displacement may be indicated by scanning devices S of well known construction. These are so mounted that the stretched and partially dried cloth passes under the scanning devices.

If the weft threads are skewed and are not perpendicular to the selvage, a variation in the frequencies is caused by the passage of the light beams across the skewed weft threads at the two scanning devices S. This variation of the frequencies will be indicated by the scanning devices, and corrective action will be initiated.

After passing through the tenter frames F, the cloth travels around lower and upper fixed guide-rolls and 21, and then passes'under a lower movable roll and over an upper movable roll 31 to additional fixed guiderolls 33 and 34. The cloth then passes through drawing or nip rolls 35 to a winding arbor 36 or other storage device.

The movable roll 30 is mounted in bearings 40 connectcd by links 41 and 42 to a pair of nuts 43 and 44. The movable upper roll 31 is similarly provided with bearings connected by links 51 and 52 to the nuts 43 and 44 previously described.

The nuts 43 and 44 are mounted on threaded portions of a shaft 55 which has a chain-and-sprocket connection to a reversible motor M2, as shown in Fig. 2.

The two scanning devices S and the motor M2 are all connected to a control panel P and in such manner that an indication of skew or displacement in one direction will cause the motor M2 to rotate the shaft 55 in a direction to move the nuts 43 and 44 toward the left in Fig. 3, and an indication of skew or displacement in the opposite direction will cause the motor M2 to rotate the shaft 55 in a reverse direction and to thereby move the nuts 43 and 44 to the right in Fig. 3.

When the nuts are moved to the left, the left-hand ends of the movable rolls 30 and 31 will be separated and the right-hand ends will be drawn closer together, thus displacing the rolls in such manner as to correct an indicated skew or displacement. If the nuts are moved to the right, a corresponding but opposite displacement of the rolls 30 and 31 takes place.

The control panel P has provision 57 by which a timelag is introduced which is just long enough to permit an indicated portion of cloth to travel from the scanning devices S to the fixed roll 21 before the correctivemovement of the rolls 30 and 31 has been effected. Consequently that portion of cloth which showed skew or displacement at the scanning device is the same portion of cloth which is passing through the correcting rolls 30 and 31 when the indicated correction has been applied to the rolls.

A supplemental or feed-back device 60 is associated with the shaft 55. The purpose of this device is to control the position which the rolls 30 and 31 will take, depending on the detection of the amount and direction of skew from the scanning devices S. This device is so adjusted that the position taken by the rolls 30 and 31 will be such as to deliver the cloth as it leaves the correcting rolls in correct transverse alignment as to its weft threads.

The detailed construction and operation of the scanning devices S, control panel P, and the feed-back device 60 in themselves form no part of the present invention.

In actual operation, the installation of the correcting mechanism beyond the cloth delivery station instead of in advance of the scanning devices has been found to be extremely advantageous, and the quality of the delivered cloth is substantially improved.

Having thus described my invention and the advantages thereof, it will be understood that the invention is not to be limited to the details herein disclosed otherwise than as set forth in the claim, but what is claimed is:

In a tenter frame having tenter chains and a succeeding cloth delivery station, in combination, screw-scanning devices mounted at the opposite sides of the cloth and in advance of said tenter chains and said delivery station, separate weft-correcting mechanism additional to said tenter chains and mounted beyond said tenter chains and said delivery station in the direction of cloth travel, control means for said correcting mechanism which is responsive to the indications of the skew-scanning devices, and timing means to delay corrective action by said weftcorrecting mechanism until that portion of cloth which was indicated as requiring correction has reached said correcting mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 

